We would like to understand the mechanisms by which hormones and other effector molecules regulate the expression of genetic information, and the ways in which this information is organized in eukaryotic cells. To understand these processes in general, we propose to focus on a particular system in which certain elements involved in the expression can be purified and can be subsequently utilized under defined conditions. We hope to study the regulation of the expression of the gene for growth hormone in cultured pituitary cells. We have obtained messenger RNA for growth hormone in reasonably pure form, and have shown that this is regulated by glucocorticoid and thyroid hormones. Growth hormone production in these cells is also regulated by a number of other hormones such as estrogens, thyrotropin releasing hormone (TRH), cyclic AMP, calcium, etc. We plan to further purify growth hormone mRNA and to synthesize a cDNA product from this. We plan to clone the cDNA and use it to study the regulation of growth hormone mRNA. In addition, we hope to purify the gene for growth hormone (and the sequences adjacent to it) by utilizing molecular cloning techniques combined with restriction endonuclease and other enzymatic procedures. The number of growth hormone gene copies, the proximity of the growth hormone gene to other related genes, and the presence of binding sites on the DNA near the structural gene for hormone receptors and other possible regulatory molecules will be investigated. The gene and chromatin from the pituitary cells will be used in reconstitution experiments to determine the functions required for its expression and regulation. We will explore the possibility of utilizing the growth hormone gene and mRNA to synthesize growth hormone in bacteria and/or in cell-free systems. Success in these efforts would hopefully provide information about the regulation of gene expression in general, the mechanism of action of several classes of hormones, and may provide the possibility for obtaining reasonable amounts of human growth hormone which is needed for treatment and understanding of growth deficiency states.